lkml.org 
[lkml]   [2014]   [Jul]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] aio: protect reqs_available updates from changes in interrupt handlers
On Mon, Jul 14, 2014 at 07:30:43PM +0200, Jens Axboe wrote:
> Why not just makes this:
>
> local_irq_save(flags);
> kcpu = this_put_ptr(...);
> ...
>
> and get rid of the preemption bits, it's a bit redundant now you need to
> kill local interrupts anyway.

*nod*. I'll add the following cleanup patch, as the first version already
got merged into another tree.

-ben

diff --git a/fs/aio.c b/fs/aio.c
index 1c9c5f0..104da62 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -832,10 +832,8 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
struct kioctx_cpu *kcpu;
unsigned long flags;

- preempt_disable();
- kcpu = this_cpu_ptr(ctx->cpu);
-
local_irq_save(flags);
+ kcpu = this_cpu_ptr(ctx->cpu);
kcpu->reqs_available += nr;

while (kcpu->reqs_available >= ctx->req_batch * 2) {
@@ -844,7 +842,6 @@ static void put_reqs_available(struct kioctx *ctx, unsigned nr)
}

local_irq_restore(flags);
- preempt_enable();
}

static bool get_reqs_available(struct kioctx *ctx)
@@ -853,10 +850,8 @@ static bool get_reqs_available(struct kioctx *ctx)
bool ret = false;
unsigned long flags;

- preempt_disable();
- kcpu = this_cpu_ptr(ctx->cpu);
-
local_irq_save(flags);
+ kcpu = this_cpu_ptr(ctx->cpu);
if (!kcpu->reqs_available) {
int old, avail = atomic_read(&ctx->reqs_available);

@@ -876,7 +871,6 @@ static bool get_reqs_available(struct kioctx *ctx)
kcpu->reqs_available--;
out:
local_irq_restore(flags);
- preempt_enable();
return ret;
}

-ben
--
"Thought is the essence of where you are now."


\
 
 \ /
  Last update: 2014-07-15 05:41    [W:0.070 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site